CH639148A5 - HIGH SPEED CIRCULAR FRAME FOR THE PRODUCTION OF TUBULAR FABRICS FROM WIRES, FLATS OR TAPES OF SYNTHETIC AND NATURAL SUBSTANCES. - Google Patents

Description

The present invention relates to a circular loom for the continuous weaving of threads, strips or tapes of synthetic substances, perfected so as to allow high rotation speeds, and therefore high productivity, with a particularly low noise index.

As is known, traditional circular looms for the production of tubular fabrics in general and in particular of tubular fabrics consisting of strips or strips of plastic material, have two sets of healds arranged on two concentric circles and subjected to alternate movements of ascent. and descent to realize the alternate separation of the warp threads; the warp threads are guided through a cylindrical comb and then deflected within a vertical hollow cylindrical body (fabric calibrator) on whose upper circular edge the tubular fabric is formed by introducing the weft threads into the warp threads. The weft threads are fed by one or more shuttles, carrying bobbins of thread on board, and are rotated on the circular comb and guided on it by means of suitable guide shoes. The shuttles, rotating between the alternately open areas of the warp threads, feed their weft thread between the warp threads themselves according to a spiral that closes on the edge of the vertical cylindrical body, also commonly called "buse"; the tubular fabric therefore forms continuously on the circular edge of the buse; from here it is constantly pulled through the buse itself and wound on a reel.

In these types of circular frames, the kinematic mechanisms generally adopted for the alternate movement of the healds consist of a camshaft, rotating in synchronism with the frame, which cams act on a lever to amplify the stroke and, through tie rods and referrals subject to opposing springs, make the relative heddle perform the necessary stroke.

These kinematic control mechanisms for healds have, in practice, various drawbacks which can be briefly summarized as follows;

- the reduced dimensions of the cams due to the need for space combined with the necessary amplification of the strokes allow to obtain only an approximate control of the final stroke of each heald, that is of the inversion points, upper and lower, of the heddle stroke;

- the inevitable clearances of the linkage used cause a considerable noise and increase the risk of breakage and / or failure due to the high number of components;

- the opposing springs limit, due to the effect of harmonic frequencies that do not agree with the strokes required for the healds, the speed of the whole frame, and finally

- the weight and inertia of all the parts subject to alternating movement and the friction of the joints also contribute to limiting the speed of the frame.

Furthermore, the majority of circular looms of the known type have the drawback that the shuttle carrying the weft thread reel always remains enclosed between the warp threads, with the loom both moving and stopped, so that it is very difficult to replace the coils. discharges both the rewinding operation of the weft thread, in case of a break; in known frames,

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finally, there are no particular loosening devices for the loom which are capable of preventing, in the event of weft yarn breakage, the formation of weft voids in the fabric.

The aim of the present invention is therefore to provide a circular loom for the production of tubular fabrics made up of threads, strips or strips, and in particular from strips and / or threads of thermoplastic polymers improved in order to overcome the drawbacks and limitations presented by the frames of a known type and above all such as to allow regular operation at a much higher rotation speed than that obtainable in known frames, with the advantage of a noise contained within normally acceptable limits.

Another object of the invention is to provide a circular frame of the specified type using heavier control and stopping kinematics capable of allowing an exact control of the final travel of the heddles, a significant decrease in the breakages of the warp and weft threads and a excellent reliability of all the equipment due to the limited number of moving components involved and the total absence of return springs and the like.

These and other objects, which will be more clearly highlighted by the detailed description that follows, are achieved by a circular frame for tubular fabrics made up of threads, strips or strips of artificial and natural synthetic substances and particularly of synthetic polymer strips, of the type with vertical healds arranged on two concentric circles and with pulling and winding of the flattened fabric downstream of the shuttles, characterized by the fact that it includes a single double profile desmodromic rotating cam for the alternate control of all the healds, said cam being constituted from a hollow cylinder, placed coaxially to the fabric calibrating cylinder and rotating in synchronism with the loom itself, on whose external cylindrical surface are obtained two closed profile and substantially cycloidal cam-guides, of which one constitutes the control cam for external healds and the other for internal healds, with said paths e-guide being associated with sliding blocks integral with support carriages for the healds mounted sliding within fixed vertical guides, so as to impart to the two sets of healds, at each complete turn of said cam cylinder, their alternate movements upward and descending, said vertical healds being also axially elastically constrained to the respective support carriages so that they can all be automatically locked in a low position by hooking their lower ends on as many swinging hooks and movable in axis with the heddles themselves so as to retain all the warp threads, inserted in the slots of the healds, at a level lower than the sliding plane of the shuttles, thus leaving the shuttles themselves free and in view, to allow the knotting of the weft threads in case of breakage and replacement of the unloaded coils.

More particularly, said system for hooking and stopping the healds in a low position consists of a series of hooks hinged on a fixed ring, each at the axis of a heddle and all kept deflected or inclined with respect to the healds by a traction spring , all the tension springs of each hook being pivoted on a revolving platform such as to move the fulcrums of said springs until the hooks are arranged in axis with the respective healds and therefore allow their hooking and stopping, in a low position, during their downward stroke, the command of said revolving platform, adapted to move the hooks in axis with the heddles, being imparted automatically, or manually, both in case of breakage of the weft thread, and to allow the replacement of the reels.

Furthermore, the loom in question, according to a further embodiment thereof, is provided with devices designed to exclude or limit as much as possible the possibility of weft voids forming as a result of broken weft threads, and also to allow easy reassembly of the weft threads in the event of their breakage and a quick and equally easy replacement of the discharged coils.

The frame according to the invention also provides, according to a particular embodiment, a device for stopping the heddles control and delayed rewinding the fabric, which is suitable for limiting the formation of weft voids, which device comprises an electromagnetic clutch or similar associated with the main motor of the loom and activating the fabric pulling unit, said clutch being able to remain, on an electric signal imparted by the shuttles, the towing device in case of weft yarn breakage and to restart the towing itself lagging behind the start of the loom, so as to obtain a thickening of the weft such as to fill the void left previously.

15 The construction and functional characteristics of the improved frame according to the invention described in more detail below, in relation to a preferred and non-exclusive form of practical realization, with reference to the attached drawings, given purely by way of non-limiting example in which:

20 fig. 1 schematically shows, partly in view and partly in section, the main constitutive elements of a circular loom for tubular fabrics, with warp threads in a spread position;

fig. 2 shows, partly in view and partly in section, the desmodromic cam device for controlling the healds, made according to the invention;

fig. 3 schematically shows two healds and relative control kinematic mechanisms of which only the internal heddle is locked in the low position;

fig. 4 shows the same embodiment of fig. 3, with en-30 both internal and external healds locked in the low position; Figures 5 and 6 show, on an enlarged scale, a hook device for locking the healds in a low position, in which the same hook is respectively in the out of engagement position and in the stable hooking position with the heald; 35 fig. 7 shows, again schematically, the main constituent elements of a loom with the warp threads gathered under the sliding plane of the shuttles after locking the relative healds in a low position; while fig. 8 shows, schematically, a device for delaying and delayed starting of the loom, suitable for avoiding or limiting the formation of weft voids on the fabric, in case of breakage of the thread itself.

With reference to these figures, and in particular to figures 1 and 2, a circular frame for the production of tubular fabrics is generally made up of two series of healds 1 and 2, arranged on two concentric circles and subjected to alternate motion, by a fixed cylindrical comb 3 consisting of lamellae 4, radially equally spaced, and locked between two opposite support rings 5 and 6, by shuttles 7 which can be rotated on the comb itself and guided by opposed shoes 8 and by a calibrating cylinder 9, placed centrally to the circles formed by healds 1 and 2, in whose upper peripheral edge 10 the fabric 11 is formed. Healds 1 and 2 carry the warp threads 12 - 13, coming from a continuous feeder (not shown), dividing them alternately in the vertical plane. 55 coves; the warp threads pass between the lamellas 4 of the comb and rejoin the circular edge 10 of the calibrator. One or more reels 14 of weft thread (not shown) open the way between the warp threads by means of the ring 15 integral with the shuttle 7. The ascent and descent of the warp threads are programmed in order to take place , with rotating reels, between the free spaces between the reel and the reel, while the weft thread that unwinds from the rotating reels is inserted helically between the warp threads right on the edge 10 of the calibrator. The fabric 11 thus formed is stretched and dragged through the calibrator 9 and turned onto the reel by means of a suitable pulling and winding device not shown in the figures.

The comb 3 and the type of shuttle 7, shown in Figure 1, constitute improvements which are the subject of

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pending patent application pursuant to the same Applicant.

According to the present invention, a kinematic mechanism suitable for controlling the healds of a frame of the type schematically shown in Figure 1 and briefly described above, is shown in Figures 2 to 4.

With particular reference to Figure 2, said kinematic control mechanism for healds 1 and 2 consists of a cylindrical cam 16, with double profile, mounted externally and coaxially to the calibrating cylinder 9 and rotating in synchronism with the frame; the motion is transmitted by a pinion 17, gripping the ring gear 18 inside the cam, which is in turn driven by a shaft 19 which is moved by a motor 20 (fig. 8) with the interposition of an electromagnetic clutch 21. cylindrical cam 16 is guided between bearings 22 anchored on a base support 23.

On the external surface of the cam 16 there are two grooves 24-25, having a substantially cycloidal shape, which constitute the real closed profile cams intended to make the heddles travel their alternate up and down strokes. To this end, shoes 26 and 27 respectively are engaged within the grooves 24 and 25 to which the carriages 28 and 29 are made integral.

Each internal heald 2 (or group of healds) is connected to the trolley 28 by means of two tie clamps 30-31 which are clamped on the heald with the interposition of a spring 32, suitably preloaded and inserted between the upper clamp 30 and the upper part of the trolley 28. The heddle 2 is therefore free to slide vertically within the carriage if the spring 32 is further compressed by pushing the heddle 2 downwards or the carriage 28 upwards with the heddle locked; in the latter case the lower clamp 31 remains detached or better set back from the carriage 28.

Likewise, the external healds 1 are anchored to the trolley 29 by means of the tie clamps 30 'and 31' and relative spring 32 '(fig. 3 and fig. 4).

In Figures 3 and 4, on the other hand, the carriages 28 and 29 are connected to the healds 1 and 2 respectively, that is to say in a different way from that shown in Figure 2; in figure 4 the cylindrical cam 16 has been rotated with respect to the position shown in figure 2.

The main function of the preloaded springs 32 and 32 'is to create a fairly rigid constraint only vertically between the carriage and the heddle rod, leaving the latter free to move, with limited play, on the horizontal plane so as to be free from the need for a very precise alignment.

The springs 32-32 'also allow the healds to be pushed down manually regardless of the position taken by the roller runners 26-27 within the profiles 24-25.

With this construction with closed-profile cams, obtained in a single rotating cylindrical body of large diameter and dynamically balanced, phase shifts between the healds are practically avoided and gentle and controlled accelerations and absence of noises are ensured; moreover, no limitation derives from the frequency of the alternations (number of stops) of the heddles themselves due to the total absence of return springs continuously stressed and the low inertia of the mobile crews.

Still according to the invention, to facilitate both the re-knitting of the weft threads in the event of breakage and the replacement of the discharged bobbins, a device for locking the healds in a low position and practically under the shuttles sliding on the comb is provided.

Figure 7 shows the position taken by the warp threads 12-13 with respect to the shuttle 7 when the healds 1 and 2 are locked in the low position; in this position the warp threads in fact pass between the sheets 4 of the comb 3 at a level lower than that of the guide shoes 8 of the shuttle and therefore the coil 14 remains free and visible and can be extracted with.

ease by moving it from the position 14 to the dashed position 14 ', after rotating the guide ring 15 by about 90 °, according to the arrow A of fig. 7, and stopping it in the position 15'.

s The device for locking the healds according to the invention (Figures 3-4-5e6) consists of a rotating ring 33, placed coaxially to the base of the cylindrical cam 16, above which another fixed ring 34 is coaxially positioned, integral with the base of the frame. The lower ring 33 and the upper ring 34 are connected to each other by one or more preloaded springs 35 (fig. 6) which tend to rotate the mobile ring 33 according to the arrow B; the rotation of the ring 33 is prevented, during the operation of the frame, by a pole 36, mounted vertically sliding in a fixed guide 37, and subject to a driving solenoid 38; in the position shown in figure 6 the ring 33 is held still by the pole 36 engaged against an appendage 39 protruding from the mobile ring 33.

On the fixed ring 34 are hinged, in axis with the individual lic-20 ci 1 - 2, rod-shaped hooks 40 which are kept deflected = with respect to the axis of the individual healds by a traction spring 41 anchored at one end to the hook 40 and with the end opposite the movable ring 33; in the disengagement position (fig. 5),

each rod-shaped hook 40 is kept supported against a 25 ledge 42 fixed to the fixed ring 34 and the hinging point P is moved, for example, to the right in fig. 5; a rotation of the ring 33 brings the point P to the position Pi (fig. 6) with the stop of the hook 40 against a stop 43 in a position ready to engage its upper hook 40 'in-30 on a similar hook 1' obtained at lower end of heald 1 when it reaches its lower end position.

The locking of the healds in the low position takes place automatically both in the event of a weft thread breaking and upon operator's command via actuation devices interlocked to the reels and relative weft thread or by means of a button.

The operation of the heald locking device takes place in practice as follows: the carriages 28-29 (figures 3 and 4) are made to go up and down by means of the respective shoes 26-27 which have been poured into profiles 24-25 of the cylindrical cam and during the weaving the hooks 40 are kept deflected with respect to the heald axis (fig. 5), ie in a plane different from that of movement of the healds themselves.

In case of weft thread breakage, or by command of the operator, the solenoid 38 is automatically energized so that the stop post 36 which keeps the ring 33 blocked against the attraction of the springs 35, is activated and brought out of the appendage 39 thus leaving the ring 39 free to rotate. The preloaded spring 35 then rotates the ring 33 according to the arrow B (fig. 6) so that the hinging point of the spring 41 passes from the position P to the position P \ The moment exerted on the hook 40 by the spring 41 is reverses and so the hook is brought and held against the stop 43, i.e. in a vertical position and in axis with the respective heddle.

55 As soon as the heddle 1, in its downward stroke, meets the hook 40 ', it remains hooked to it with its terminal hook 1' (fig. 6).

The coupling sequence of healds 1 and 2 is shown in figures 3 and 4. When the heald 2 has engaged in the low-position as previously said, to obtain the hooked also of the heald externally the cam central 16 dèvé make a further partial rotation in conségùèitóià dèlia which, while the heddle 'I is lowered' and hooked to the pfò-6s prìb swinging hitch 40 ", if éàrrello 29 of the heddle 2 starting its ascending course compressed there spring 32 against the tie-like motif 30 allowing the end of its hook 2 '(fig. 3) to remain hooked to the oscillating hook 44;

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hinged in the fixed ring 34. In Figure 4, the two healds are both locked in the low position and in this position the tie clamp 31 of the heald 2 has remained detached from the relative carriage 28.

After knotting the weft thread (or replacing the reel), a special hydraulic jack or the like, not shown in the figures, rotates the mobile ring 33 in the opposite direction, thus restoring the preloading of the springs 35 due to the attachment of the stake 36 against the appendix 39 of the movable ring.

Still according to the invention, in order to eliminate or in any case minimize the formation of weft voids in the fabric, in the event of a weft thread breakage, an electromechanical device is provided, shown in Figure 8, whose task is to make a stop differentiated movement of the loom and a delayed recovery of the rewinding of the fabric, such as to overcome the aforementioned drawback.

The device object of the invention consists of a pulley 45, coaxial with the motor shaft 19 and a pulley 46 mounted on the shaft 47 of a towing device of a known type not shown, connected to each other by a belt 48; an electromagnetic clutch 49 is arranged between the pulley 46 and the shaft 47 of the towing device. In the event of a weft thread breakage, signaled by a special control device arranged in the shuttle, the clutch 49 is immediately disconnected so that the fabric towing undergoes an immediate arrest.

Subsequently, the main clutch 21 is also disengaged (fig. 8) and the whole frame is stopped. In the meantime the shuttles have made some laps so that, if no thread had broken, the plot would have thickened; however, the breaking of the wire leaves a certain weft void. After the knitting of the weft thread, the loom is first screwed on by inserting the main clutch 21 whereby the loom begins to weave regularly; once the operating speed has been reached (after a predetermined time and variable in relation to the type of weft chosen), the clutch 49 is automatically inserted, so that the weaving cycle continues regularly. With this sequence (delayed stop of the loom with respect to the towing and start of the loom in advance of the start of the loom), weft thickening which, by sliding vertically between the yarns of the order, will fill the void left previously. Finally, the assembly consisting of the closed double profile cylindrical cam and the heald trolleys is kept constantly lubricated by forced circulation of lubricating oil.

In the practical realization of the improved frame according to 20 the invention, structurally and functionally equivalent modifications and variations can obviously be made without departing from the scope of protection of the invention itself. Likewise, the dimensions of the loom, the type and dimensions of the threads and / or strips to be woven, the number of shuttles and other details may vary according to requirements while remaining within the scope of the invention as described above and claimed .

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Claims (6)

639 148 1. Circular loom for tubular fabrics consisting of threads, strips or strips of synthetic, artificial and natural substances and particularly of strips of synthetic polymers, of the heald type (1, 2) vertical arranged on concentric circles and with fabric pulling and winding flattened downstream of the shuttles, characterized in that it comprises a single double profile desmodromic rotating cam (24, 25) for the alternate control of the healds, said cam being constituted by a cylinder. hollow dro (16) rotatable coaxially to the fabric calibrating cylinder (9), on whose external cylindrical surface are obtained two closed profile and substantially cycloidal cam-guides, one of which constitutes the control cam for the external healds and the other one for the internal healds, with said guide cams being associated shoes (26, 27) integral with trolleys (28, 29) for supporting the healds mounted sliding within fixed vertical guides, so as to impart, to the two sets of healds, their alternating movements up and down, said vertical healds being also axially linked in an elastic way (32 - 32 ') to the respective support trolleys (28 - 29) so that they can all be locked automatically , in a low position, by hooking their lower ends (1 ') on as many oscillating hooks (40') and movable in axis with the heddles themselves so as to retain all the warp threads at a level lower than the sliding plane of the shuttles thus leaving the shuttles themselves free and in sight. Circular frame according to claim 1, characterized in that each vertical heddle (1, 2) is mounted on the respective carriage (28, 29) by interposing a preloaded spring (32 - 32 '), inserted between two clamps (31 - 31 ') stuck in the heddle and one of which, the lower one, is placed under and in contact with the trolley itself, so as to constrain the heddle rod only vertically to the respective trolley, leaving the heddle itself the possibility of sliding within the trolley itself by further compression of said spring. 2 Circular frame according to claims 1 and 2 characterized in that it provides, for locking the healds in the low position, a series of hooks (40 ') hinged on a fixed ring (34), each at the axis of a heddle and all kept deflected or inclined with respect to the healds by a traction spring (41) all the traction springs of the hooks being fulcrated on a rotating platform (33) associated with said fixed ring by at least one traction spring (35) such as to move the fulcrums of said springs until the hooks are arranged in axis with the respective healds and therefore allow the hooking and stopping of the same, in low position, during their downward stroke, the control of said rotating platform, suitable for move the hooks in line with the healds, being imparted automatically, or manually, both in case of weft thread breakage and to allow the replacement of the reels. Circular frame according to claims 1 to 3, characterized in that said revolving platform (33), adapted to bring the hooks in axis with the respective healds, substantially consists of a revolving ring, coaxial with said fixed ring (34) and associated with it by means of preloaded springs (35), said rotating ring being kept locked, so as to guarantee the preloading of said springs, by a mobile stop device (36 - 39) adapted to be activated by a signal emitted by the shuttles or on manual control, in case of weft thread breakage or to allow the replacement of the coils and / or shuttles. Circular loom according to the preceding claims, characterized in that it provides, to avoid the formation of weft voids in the fabric in case of weft thread breakage, a differentiated stop device for the loom and delayed rewinding of the fabric, consisting of an electromagnetic clutch (49) associated with the main motor (20) of the loom and actuating the fabric pulling unit, said clutch being able to stop, on an electric signal imparted by the shuttles, the towing device in case of weft yarn breakage and to restart the towing itself in delay with respect to the start of the frame, so as to obtain a thickening of the weft such as to fill the void left previously. Circular frame according to the preceding claims, characterized in that said cylindrical cam (16) for controlling the healds and said shoes and related carriages; they are kept constantly lubricated by forced circulation of lubricating fluid. • <